Christiane E.L. Dammann, M.D. is currently a research and clinical fellow in the Division of Newborn Medicine at New England Medical Center and a research fellow in the Division of Signal Transduction at the Beth Israel Hospital. She is applying for this award to develop a career as an independent scientist in Neonatology with her research focused on fetal lung development. She will accomplish this goal with the help of her two mentors Dr. Nielsen and Dr. Cantley. Pulmonary surfactant consists of phospholipids and apoproteins and is critical for lung maturation. Surfactant deficiency during fetal lung development contributes to neonatal distress syndrome. Fibroblast- Pneumocyte-Factor (FPF) is a fibroblast derived polypeptide differentiation factor that regulates surfactant synthesis in lung type II epithelial cells. We have strong evidence that Neuregulin-1 (NRG1), a stromal-derived growth factor previously implicated in mammary gland epithelial cell maturation, is a critical component of FPF. For our preliminary studies we have used MLE 12 cells, which display characteristics of fetal type II cells. We now propose to investigate further the role of NRGs and their receptors in regulating surfactant synthesis during lung development using primary fetal mouse cells. The specific aims of this proposal are threefold. First, the role of the NRGs in the regulation of fibroblast-type II cell communication leading to surfactant synthesis will be determined. Second the regulation of NRG expression / production during lung development will be investigated. Third, the question which of the erbB receptors and intracellular ligands are involved in the NRG signaling pathway in mesenchymal-type II cell communication will be studied. The goal is to gain further insight into the regulation of surfactant synthesis. This should contribute to the development of diagnostic and therapeutic strategies that reduce the burden of acute and chronic lung disease among preterm infants.